Navel Oranges: The Mutant Clones in Your Kitchen

August 20, 2010

Oranges come in many varieties, but the navel orange, pictured right, is probably one of the most common. Easily identifiable from the outside by the navel-like circle at one end, these oranges also have additional, tiny wedges just inside the “navel.”

All these features exist because the navel orange in your kitchen is a clone — a clone of a mutant orange dating back almost two hundred years ago.

In the early 1800s, the first known navel orange grew on a sour orange tree at a Brazilian monastary and was discovered by a missionary. The missionary was intrigued by the seedless orange, and, via cutting and grafting — a pair of techniques used to asexually reproduce plants (the linked-to Wikipedia pages explain both well) — grew multiple new trees, full of navel oranges. He sent a few trees to the a man named Wililam Saunders at the U.S. Department of Agriculture. Saunders gave three trees to a California-bound neighbor, where the fruit took and was instantly popular.

The navel orange’s popularity only grew from that point out, even despite one salient fact: the original orange was a mutant. Orange historian Vince Moses told National Public Radio’s All Things Considered that the the tiny wedges are actually a conjoined twin — a second orange — which grows inside the primary fruit’s peel. The navel is actually the formative peel of the secondary fruit, developing on the side opposite the stem.

Interestingly, this genetic trait never should have propigated throughout the years, as the orange is also seedless. Rather, navel oranges have been cultivated via cutting and grafting since their discovery. The result: every single navel orange is, genetically, identical to the first mutated one found by that missionary centuries ago.

Bonus fact: It’s well known that human navels — our bellybuttons — are marks left from our removed umbilical cords. But interestingly, bellybuttons are actually scars. As such, they’re not body parts defined by our genetics, and are one of the easiest ways to distinguish newborn identical twins from one another.

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